This definitions covers Key Definitions within Water Regulation for GCSE Biology. Topic 7: Water Regulation It is section 5 of 11 in this topic. Make sure you can use the exact wording confidently, because definition marks are often lost through vague language.
Topic position
Section 5 of 11
Practice
15 questions
Recall
20 flashcards
Key Definitions
ADH (antidiuretic hormone): A hormone produced by the hypothalamus and released by the pituitary gland that increases water reabsorption in the kidneys.
Osmoregulation: The regulation of water and salt levels in the blood and body fluids to maintain a constant internal water potential.
Nephron: The functional unit of the kidney; a microscopic tubule that filters blood and reabsorbs useful substances.
Filtration: The first stage in nephron function; blood is filtered under high pressure in the glomerulus, removing water, glucose, urea, and salts into the Bowman's capsule.
Selective reabsorption: The process by which useful substances (glucose, some water, salts) are taken back from the nephron tubule into the blood.
Urea: A waste product formed in the liver from the breakdown of excess amino acids; excreted in urine by the kidneys.
Excretion: The removal of metabolic waste products (such as urea, CO2, and excess water) from the body.
Collecting duct: The final region of the nephron; its permeability to water is controlled by ADH, determining how concentrated the urine will be.
Aquaporin: A protein channel embedded in the cell membrane of the collecting duct. ADH causes more aquaporins to be inserted into the membrane, increasing the membrane's permeability to water and allowing more water to be reabsorbed by osmosis.